JPH0333776A - Developing device - Google Patents

Abstract

PURPOSE:To prevent a failure caused by remaining toner at the time of stopping an action by providing a control part which inverts the relation of voltage level between a developing bias voltage and a blade bias voltage for a specified time before stopping the action. CONSTITUTION:For the specified time before stopping the supply of voltage, the relation of the voltage level between the developing bias voltage Va and the blade bias voltage Vb is inverted so as to invert the line of electric force F1 with which mono-component toner 4 is moved to a developing roller 7 to the line of electric force F2 in an opposite direction, and the quantity of toner which is moved to the developing roller 7 is reduced or made none at all. Since the developing roller 7 does not convey the toner 4 to the photosensitive drum 1 just before stopping the action, the toner 4 is prevented from remaining between the developing roller 7 and the photosensitive drum 1 at the time of stopping the action.

Description

[Detailed description of the invention] [Table of contents] Overview Industrial field of application Prior art (Figure 7) Means for solving the problem to be solved by the invention (Figure 1) Working example (a) 1 Description of Examples (Figures 2 to 5) (b)
Description of another embodiment (Figure 6) (C) Description of another embodiment Effects of the invention (I!E required) The power of developing an electrostatic latent image on a latent image carrier using a monocomponent toner In order to easily prevent inconveniences caused by residual toner when the operation is stopped, a toner conveying body that conveys the toner by being in pressure contact with the latent image carrier on which an electrostatic latent image is formed is developed. and a layer thickness regulation member for regulating the toner on the toner transport body to a desired layer thickness, and a developing bias voltage is applied to the toner transport member, and the toner is applied to the layer I regulation member. In a developing device configured to apply a blade bias voltage for regulating the toner layer thickness of a conveying body, a control unit is provided to reverse the height relationship between the developing bias voltage and the blade bias voltage for a predetermined period of time before the operation is stopped. .

[Industrial application field]

The present invention relates to a one-component developing device that develops an electrostatic latent image on a latent image carrier using a one-component toner.

In image forming devices such as electrophotographic printing devices and electrostatic recording devices, powder developing devices are used to visualize electrostatic latent images formed on photosensitive drums and dielectric materials that are latent image carriers. It is being

In recent years, one-component developing devices using one-component toner, particularly non-magnetic component toner, have been attracting attention because they are easy to maintain and can be made compact.

In a one-component developing device, in order to visualize an electrostatic latent image on a latent image carrier, a toner conveying body for supplying -component toner onto the latent image carrier is brought into pressure contact with the latent image carrier. It is provided.

Therefore, when the operation is stopped, one-component toner may remain between the latent image carrier and the toner conveying member, which may cause problems.

[Conventional technology]

FIG. 7 is an explanatory diagram of the prior art.

- The component developing device has a photosensitive drum l, which is a latent image carrier,
A developing roller 7, which is a toner conveying member, is provided in pressure contact with the developing roller 7.

The developing roller 7 transfers the -component non-magnetic toner 4 to the photosensitive drum 1.
The one-component non-magnetic toner 4
A developing bias voltage Va is applied to cause the image to be attracted to the electrostatic latent image on the photosensitive drum l.

On the other hand, a layer thickness regulating member (referred to as a bias blade) 8 is provided on the developing roller rough, either in contact with it or with a certain gap therebetween.

A blade bias voltage vb for charging the negative component toner 4 and controlling the thickness of the toner layer on the developing roller 7 is applied to the bias blade 8 .

For example, if the - component toner 4 is of a positively charged type, Vb>
A bias voltage is applied such that Va is applied, and electric lines of force are generated from the bias blade 8 toward the developing roller rough as indicated by Fl in the figure, and the - component toner 4 is attracted to the surface of the developing roller 7, and the developing roller One-component toner 4 is deposited on top of 7, and the toner layer thickness is controlled to 1ljJ.

As such a -component developing device, one is known in which the developing roller 7 is kept in constant contact with the photosensitive drum I, and the other is one in which the developing roller 7- is retracted from the photosensitive drum I when printing is completed.

[Problem to be solved by the invention]

By the way, as shown in FIG. 7(B), when the operation is stopped 1- such as at the end of printing, the developing bias voltage Va and the blade bias voltage vb are turned off at the same time as driving of the developing [1-rough]. That's what I was doing.

For this reason, in a device in which the developing roller 7 is kept in constant contact with the photosensitive drum I, when the operation is stopped, one-component toner remains between the developing roller 7 and the photosensitive drum I, resulting in a sandwiched state. .

Therefore, the quality of the sandwiched toner may deteriorate, and the photosensitive drum 1 may
There has been a problem in that toner offset occurs due to toner fusing, resulting in poor print quality.

On the other hand, in a structure in which the photosensitive drum 1 retracts the developing roller 7 when the operation stops 1, such a problem does not occur, but the mechanism is complicated and it is difficult to apply it to a small device.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a developing device that can easily prevent inconveniences caused by residual toner when its operation is stopped.

[Means to solve the problem]

FIG. 1 is a diagram showing the principle of the present invention.

As shown in FIGS. 1A and 1B, the present invention comprises a toner conveying body 7 that conveys toner 4 in pressure contact with a latent image carrier l on which an electrostatic latent image is formed; Toner 4 on conveyor 7
A developing bias voltage Va is applied to the toner transport body 7, and the layer thickness regulation member 8 controls the toner layer of the toner transport body 7. A developing device configured to apply a blade bias voltage vb for regulating the thickness, which is provided with a control unit IO that reverses the height relationship between the developing bias voltage Va and the blade bias voltage vb for a predetermined period of time before the operation is stopped. It is.

[Effect]

In the present invention, the relationship between the developing bias voltage Va and the blade bias voltage vb is reversed for a predetermined period of time before the voltage supply is stopped, and the electric force line Fl that moves the one-component toner 4 to the developing roller 7 in FIG. 1(C) is is reversed to the line of electric force F2 in the opposite direction of FIG. 1(D), thereby reducing or eliminating the amount of toner moving to the developing roller 7.

Therefore, immediately before the operation stops +h, the developing roller 7 does not convey the photosensitive drum l header 4, so that it is possible to prevent the toner 4 from remaining between the developing roller 7 and the photosensitive drum l when the operation is stopped.

Furthermore, since this can be done by switching the voltage, the structure can be easily realized.

〔Example〕

(a) Description of one embodiment FIG. 2 is a configuration diagram of an embodiment of the present invention.

In the figure, l is the aforementioned latent image carrier, which is composed of an OPC photosensitive drum, has a diameter of 60 mm, and a surface speed of 70. mm
/s, and after the surface is charged with 1650 V and Hf7 by a corona charger (not shown), the information to be recorded is transferred by a laser scanning optical system (not shown), an exposure optical system (L E I), etc. By irradiating light accordingly,
An electrostatic latent image is formed.

Reference numeral 2 denotes the above-mentioned one-component developing device, which has the following configuration in order to visualize an electrostatic latent image by supplying -component non-magnetic toner onto the OPC photosensitive drum 1. .

That is, the developer container 3 stores a one-component non-magnetic toner (polyester toner) 4 having an average particle size of about 10 μm.
The agitator 5 rotates in the six directions of arrows within the developer container 3 and causes friction with the -component non-magnetic toner 4, thereby charging the one-component non-magnetic toner 4 to negative polarity (=).

The paddle roller 6 is a first roller formed at the bottom of the developer container 3.
By rotating in the direction of arrow B, the non-magnetic toner 4 present at the lowest position in the developing container 3 is pumped up and supplied in the direction of a developing roller 7, which will be described later.

The aforementioned developing roller 7 has a surface speed of 175 m in the direction of arrow C.
It rotates at m/s and is opened with the non-magnetic toner 4 conveyed by the paddle roller 6 adsorbed on its surface.
, C is conveyed to the contact portion with the photosensitive drum I, and the electrostatic latent image on the OPC photosensitive drum 1 is visualized by IIT.

This developing roller 7 has, for example, a diameter of 20 mm, a volume resistance value of IO4 to 1010 Ω·m (optimally 105 Ω·m),
Polyurethane foam (open cell) with a hardness of 10 to 35° (measured with an Asker-C hardness meter: optimally 100)
The developing bias voltage V
a (-30OV) is applied.

Further, the developing roller 7 is pressed with a linear pressure of 22 to 50 g/cm( Optimally, it is pressed at a pressure of 43 g/cm) and is pressed against the OPC photosensitive drum rotating in the direction of the arrow so that the nip width is 1 to 3.5 mm.

The aforementioned layer thickness regulating bias blade 8 is made of aluminum or stainless steel, and is rotatably provided around a shaft 8a, and is biased toward the developing roller 7 in the direction of arrow X by a biasing means such as a spring (not shown). Linear pressure 26g/m
m, the thickness of the toner layer on the developing roller 7 is regulated to a constant value, and a blade bias voltage vb of -400V is applied, and the -component non-magnetic toner 4 is
In this embodiment, the thickness of the toner layer is controlled by charging the toner to a negative polarity and applying a voltage.

Like the developing roller 7, the collecting roller 9 has a volume resistivity of 1.
It is made of high-molecular foam polyurethane having a hardness of about 0'Ω·m and a hardness of about 10 to 70'', and is disposed within the second four parts 3b of the developer container 3.

This collection roller 9 has a diameter of 11 mm and a circumferential speed of 70 mm.
/s, the nip thickness is set to 1 mm, and further,
Recovery bias voltage (-300V to -
250 V) is applied to mechanically and electrically collect the one-component non-magnetic toner 4 from the surface of the developing roller rough, and eliminate mechanical and electrical history from the developing roller 7.

FIG. 3 is a block diagram of an embodiment of the present invention.

In the figure, the same components as those shown in FIG. It performs application, switching, and cutting control.

11a is a high-voltage power supply that applies, switches and disconnects the blade bias voltage vb of the bias blade 8 according to instructions from the control unit (hereinafter referred to as MPLJ) 10; ■
b is a motor control unit, which includes an agitator 5 and a paddle roller 6.
, a developer motor (not shown) that drives the developer roller 7 and collection roller 9, which is controlled by instructions from the MPU10;
llc is a high-voltage power supply, which applies a developing bias voltage V to the developing roller and collecting roller 9, respectively, according to instructions from MPU10.
a, for applying a recovery bias voltage Vc.

FIG. 4 is a processing flow diagram of an embodiment of the present invention, and FIG. 5 is an explanatory diagram of the operation of an embodiment of the present invention.

During normal printing, a blade bias voltage Vb = +-400 is applied to the bias blade 8, a developing bias voltage Va-+300 is applied to the developing roller, and a collection bias voltage Vc = +300 is applied to the collection roller 9, as shown in FIG. 1(C). Since Va>Vb, electric lines of force are generated from the bias blade 8 toward the developing roller 7, and the toner 4 is transferred to the developing roller 7.
It is assumed that the person is attracted to

■ When a device stop command arrives, M P tJ 10 instructs the high voltage voltage alga to switch the bias, and the high voltage voltage filter
Switch the blade bias voltage vb of la to -200.

As a result, the developing bias voltage Va (-1300)
The height relationship is reversed, and Vb>Va, as shown in Figure 1 (D).
As shown in FIG. 2, the direction of the electric lines of force between the bias blade 8 and the developing roller 7 is reversed.

Therefore, a force is generated in the direction in which the negatively charged toner 4 is peeled from the developing roller 7 toward the bias blade 8, and the thickness of the toner layer formed on the developing roller 7 is suppressed.

■ MPU10 sets the time to the built-in timer,
Start the timer.

This time is determined by the distance F41 from the bias blade 8 to the pressure contact portion of the photosensitive drum I on the circumference of the developing roller rough.
In relation to the surface speed vs. of the developing roller 7, Q
/vs or more.

- When the timer times up, the MPU10 issues an OFF instruction to the high voltage power supplies 11a and llc and turns off the developing bias blade 8 because the developing roller has rotated to the pressure contact part with the photosensitive drum 1 after switching the lE pressure of the bias blade 8. The voltage Va, the brake bias voltage vb, and the recovery bias voltage Vc are disconnected.

(2) Then, the MPU 10 turns off the pre-charger (not shown), turns off the aforementioned developer motor from the motor control section 11b, turns off the drum motor (not shown) that drives the drum l, and ends the stopping operation.

In this embodiment, since the blade bias voltage is reversed from the negative side to the positive side, the magnitude of the reversed electric lines of force is large, and the negative toner 4 is not attracted to the developing roller 7 at all and does not adhere to it.

(b) Description of other embodiments FIG. 6 is an explanatory diagram of the operation of another embodiment of the present invention.

In this example, the blade bias voltage vb is -400
It is designed to turn off from V to O■.

That is, in step (3) of FIG. 4, the blade bias voltage vb was turned off from -400V to ov,
The rest is exactly the same as FIG. 4.

Therefore, in the step, Vb
>Va, the lines of electric force between the bias blade 8 and the developing roller 7 are reversed, and a force is applied to the toner 4 in the direction of separating it from the developing roller 7.

In this embodiment, the blade bias voltage source 11a requires both a positive voltage source and a negative voltage source, but in this embodiment, a negative voltage source is sufficient, and the cost is reduced.

(C) Description of another embodiment In the above embodiment, the photoreceptor is a negatively charged organic photoreceptor (o
pc), the development bias voltage, toner supply bias voltage, and toner collection bias voltage were all set to negative potentials. , the developing bias voltage, the toner supply bias voltage, and the toner collection bias voltage may be set to positive potentials.

Although the present invention has been described above using examples, the present invention can be modified in various ways according to the gist of the present invention, and these are not excluded from the present invention.

〔Effect of the invention〕

As described above, according to the present invention, for a predetermined period of time before the operation stops, the relationship between the developing bias voltage Va and the blade bias voltage vb is reversed, and the lines of electric force are directed in the direction in which the toner is attracted to the toner conveying member. By reversing the toner in the direction of 211#, it is possible to prevent toner from remaining between the toner conveying member and the latent image carrier when the operation is stopped, and to prevent deterioration of the quality of the toner due to the remaining toner and toner offset to the latent image carrier. This has the effect of being easily preventable and contributes to obtaining stable print quality.

[Brief explanation of drawings]

Fig. 1 is a principle diagram of the present invention, Fig. 2 is a configuration diagram of an embodiment of the invention, Fig. 3 is a block diagram of an embodiment of the invention, Fig. 4 is a processing flow diagram of an embodiment of the invention, FIG. 5 is an explanatory diagram of the operation of one embodiment of the present invention, FIG. 6 is an explanatory diagram of the operation of another embodiment of the invention, and FIG. 7 is an explanatory diagram of the prior art. In the figure, 1-latent image carrier, 4-toner 7-1-toner conveying member, 8-layer thickness regulating member, l〇-control unit.

Claims (1)

[Scope of Claims] A toner conveying body (7) that conveys toner by being in pressure contact with the latent image carrier (1) on which an electrostatic latent image is formed, and a toner conveying body (7) that conveys toner on the toner conveying body (7) as desired. a layer thickness regulating member (8) for regulating the layer thickness to a layer thickness of , and applying a developing bias voltage to the toner transport body (7), and applying a developing bias voltage to the toner transport body (7); 7) In a developing device configured to apply a blade bias voltage regulating the toner layer thickness, a control unit (10) is configured to reverse the height relationship between the developing bias voltage and the blade bias voltage for a predetermined period of time before the operation is stopped.
).